Process of dehydrating materials



March 4, J. F. WAIT PROCESS OF DEHYDRATING MATERIALS Filed 1260.31, 1924d INVENTQR ATTORNEY Thisjjinve ntion relates to a process for re-'jinovin'g --'volatile or vaporizable nata process by which the heatineffect of. i an'el'ec'trical-current is employed 'ngvolajtileproducts'when such products'are, v In. cases where; ,.herej is a large"amount of the volatile 'o'r' vai-f. p 'porizable products to be removed,it w llxgene" I v ii found advantageous to employ a vacuum to i. ornnwronx, 11.1.,assrenon roiu'rronar. Amnnm a cannon '00., me, ACORPORATION. on NEW Yonx ixaocnse or nnnrnmrme- MATERIALS Applicationfiled ne emtei si iaza. Serial my 759,041.

rein-amate'riul or a mixture of -solid-materials. It relates morepartlcularly fflsma'llj-relative volume.

-era11y=be preferable to removea'lar'ge or {pl te-th y a "f the presentinvention the materials to f -ti on thereoi by ordinary dryin or 'dehyrat-,

H t-isespecially'true where itis necessary-to have Iexcelsjsivehy 'high'temperatures to comration step.

. d or. dehydrated may first be treated inan ordinary dehydrator of asingle or v fdoublefstep type that maybe steam heated or fire; heated toa suflicient'degree to remove I sethejinaj or portion of the moistureafter which ,the remainder of the operation is completedto or dehydrate"the material to the de-" input can be controlled and the facility with awhichfthe heat input can be immediately cut ofiuf This portion oftheprocess is alsoad vantageous when the product that is to be dejhydratedis to be lateral electrolyzed because incipient electrolysismaybeinitiated during the ehydration step. I I

f Biy' followingthis invention it is possible toutilize steam'heat forremovm moisture i while it is present and capable 0 being removedIwithinthe temperature limits of orfor remo'v ingprocesses and to complete t eremoval liy, wthe'jelectrical heating means.

T15 throughthe-mass while the sired f extent b utilizing the heatingeiiect "of; an electrica current. The electrical current method isespecially desirable because of a thefreadiness with which the amount ofheatcommercial steam supply sources thus heat has been utilized toremove as much "moisturea's is practically advantageous, fire heat maybe employed to remove another portion of the moisture,after which theelectrical means can be used for finishing the. dehydrating ste In somecases either the "steam heat-or t e fire heat or both may be eliminatedand the electrical heat utilized throughout the ventire process forremoval of moisture- 111 many cases it will also be {aid in removing themoisture or in permit- "ting the moisture to be removed at lower tempperaturesf." "A similar advantageous result n; prior processes ofdehydrating mates 5. ls, such as caustic alkali io'r example,fi1t 1 gasbeenffound that difliculties ,andtroublesoftenflarise'especiall whenthe .pro'ductiha s I i been partially dehy rated or whenitishasgaosbecomefconsiderabl "concentrated 'dueftoj the corrosive efl'ect of te concentratedmateriaLjhydration is takingplace:

dehydrator a Reference character-1 (Fig. 2) indicates a: closed tankorreceptacle which may, for

exampleybe of cylindricalshape. This tank 1s. provided with an overflow2. A concentric inder 3 whoselower endis open extends mto thetank l; Thecylinder 3 has a valved inlet-for the supply-of material to bedehydrated land an outlet 5 which leads to a receiver and; vacuumproducing means not shown. electrode 6 extends through an insulatedopening into the cylinder 3. The

electrode 6 is connected to one side of a source of electric .currentand the cylinder 3 which operates as the-other electrode is connected tothe other side of thesource of current.

Either alternating or direct current may be Iused, alternating currentbeing preferable where it is desired not toelectrolyze the material'thatis .to be dried and direct current may be used-incases whereelectrolysis is not objectionable or where it might aid. The

outlet-2"may lead to a receiver '8 whichmay, if. desired, be maintainedunder a vacuum. A gas supply pipe 9 leading from a source not sho'wn'mayleadto'a distributor 10 that "la-"In" the accompanying drawings, an arrangement of apparatus is illustrated .by' which the process can becarried out. In ,1 the (11-min a 1 '-Fig.-' s ows diagrammatically thear rangementjofapparatus; and 2shows more of the details of the elecmaybe effected. Reference character A indiried by means of an electriccurcates an evaporator that is heated by means of the steam coil B, thevapors therefrom serving to heat the coil 0 in evaporator D.

- The partially concentrated material flows t In this from evaporator Ainto eva orator D through the pipe E where it is rther concentratedunder vacuum that is maintained by the vacuum pump F. The concentratedmaterial then flows from the eva orator D through the pipe G into thefire eated dehydrator H where additional concentration takes lace afterwhich the material is fed into t e electrical dehydrator 1 wherethefinal concentration is caused to take place.

articular arrangement of apparatus it will be seen that the vaporspassing off from the material to be dehydrated are removed from the coilC, from the condenser and vacuum producing means F and from the venteddehydrator H and also the final dehydratorl as already ex lained. Thedehydrator H maybe heated y a gas flame or other direct fire, or it maybe externally heated by an indirect method such as hot gases orexternally applied electric heating. In the specification and claims theexpression direct fire is intended to mean a heating means whichproduces temperatures approximately equivalent to those obtained b aplication o a direct flame to the vessel. t be understood that either oneor all of the evaporators A, D and dehydrator H may be eliminated incase the materials have small enough moisture therein to make theremoval thereof economical in the dehydrator 1.

As a specific illustration of material that may be treated by thisinvention ma be mentioned a solution of a mixture 0 and potassiumhydroxide. A dilute solution may be concentrated in a two-stage steamheated evaporator, the second stage of which operates under vacuum. Thecaustic containing liquid is concentrated to a strength of about '50% inthis equipment. The partially concentrated solution is then fed mto oilfired dehydrators, likewise operating under vacuum, and wherein theconcentration is increased to above 90%. The partially dehydratedcaustic then contains less than 10% of water. This is charged throughthe feed line 4 and passes through the zone between the electrodes 3 and6 wherein it is subject-v ed to the heating efiect of the electric current. 'The heat generated causes vapors to form which riseto the top ofthe chamber 3 wherefrom they are removed through the outlet 5. Theregion 3 and the outlet 5 are preferably maintained under a vacuum togive an absolute pressure of less than 12 pounds. Provision must be madeto balance the imposed vacuum so as to maintain a flow of causticbetween the electrodes. This may be done by imposing the same vacuumconditions upon the receiver 8. The dehydrated caustic flows through thebottom of the chamber 3 upward through the tank 1 and through the outlet.2 to the receiver. The direction of flow of the solution may bechanged, if desired, so as to have the vapors evolved by the heatingefiect of the electric current while the mixture is passin u wardly,corres onding changes as to cc and vacuum eing made to permit thisdirection of flow to be maintained. The desired degree of dehydration isobtained by controlling the rate of 20W of the caustic mixture and thecurrent The process may likewise be applied to the removal of volatilesubstances such as alcohol, ether, and benzol, which may be mixed withless volatile orlsolid material and which can be caused to flow throughthe passages. I claim: f

1. In the process of dehydrating caustic alkali, the steps whichcomprise passing said alkali containing water and in a molten conditionbetween electrodes while causing-sufiicient current to flow betweensaidelectrodes to eliminate water.

2. In a process of dehydrating a mixture of caustic soda and causticpotash, the steps which comprise passing said mixture containing waterand in a molten condition'between electrodes while causing sufiicientcurrent to flow between said electrodes to evaporate water, and removingthe vapors.

3. In the processof deh dratipg molten caustic alkali, the steps whiecomprise passing said alkali containing less than 10 per cent of waterbetween electrodes while causing sufiicient current to flow'between saidelectrodes to evaporate water, and removing the vapors while maintaininga vacuum.

4. In the process of dehydrating caustic alkali the steps which comprisethe evaporation of'water from the said caustic alkali by means of steam.heat, further evaporating water by means of application of direct heatfrom a flame and subsequently dehydrating the caustic by passing it inmolten condition between electrodes while causing sufiicient current to'flow between said electrodes to evaporate moisture, and removing thevapors.

5. In the process of dehydrating caustic alkali,.the steps which comrise heating the mixture containing caustic a kali in an evaporator toremove moisture therefrom and to produce a. caustic liquor of at leastconcentration, further concentrating said caustic containing liquids ina direct fire least and passing said partially dehydrated caustic inmolten condition between ing said alkali containing water betweenelectrodes while causing sufiicient direct current to flow between saidelectrodes to eliminate water by electrolysis.

7. In the process of dehydrating molten alkaline materials, the stepswhich comprise assing said material containing moisture betweenelectrodes While causing suflicient current to flow between saidelectrodes to evaporate moisture and removing the vapors by passing acurrent of inert gas through said material during the evaporation.

8. In the process of dehydrating molten alkaline materials, the stepswhich comprise heating said materials by means of steam, causing partialconcentration thereof, heating the partially concentrated materials bymeans of the employment of direct fire and passing the concentratedmaterial between electrodes while causing suflicient current to flowbetween said electrodes to evaporate moisture, and removing the vapors.

9. In the process of dehydrating molten alkaline .materials containingan electrolyte, the steps which comprise passing said materialscontaining moisture between electrodes while causing suflicicnt directcurrent to flow between said electrodes to eliminate said moisture byelectrolysis.

In testimony whereof I affix my signature.

JUSTIN F. WAIT.

' (Sell) CERTIFICATE OF CORRECTION.

Patent No. 1,149,455. Granted March 4. 1930, m

JUSTIN F. WAIT.

- It in hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 1,line 41, for the word "lateral" read "later"; and that the said LettersPatent should be read with this correction therein that the same mayconform to the record of the one in the Patent Office.

Signed and aealed this 8th day of April, A. D. 1930.

' M. J. Moore, Acting Conrniaeioner of Patents.

